Understanding Amphoteric Oxides

An amphoteric oxide exhibits dual chemical behavior. It can react with both acids and bases to form salt and water, similar to how both acidic and basic oxides behave.

Analyzing Oxide Properties

We need to identify the oxide among the options that can react with both acids and bases.

• Phosphorus pentoxide ($P_2O_5$): This is a classic example of an acidic oxide. It reacts with water to form phosphoric acid ($H_3PO_4$) and neutralizes bases.
  Example reaction with base: $P_2O_5 + 6NaOH \rightarrow 2Na_3PO_4 + 3H_2O$
• Zinc oxide ($ZnO$): This oxide demonstrates amphoteric behavior. It reacts with acids to form zinc salts and with strong bases to form zincates.
  Reaction with acid: $ZnO_{(s)} + 2HCl_{(aq)} \rightarrow ZnCl_{2(aq)} + H_2O_{(l)}$
  Reaction with base: $ZnO_{(s)} + 2NaOH_{(aq)} + H_2O_{(l)} \rightarrow Na_2[Zn(OH)_4]_{(aq)}$
• Magnesium oxide ($MgO$): This is a typical basic oxide. It reacts readily with acids but not with bases.
  Reaction with acid: $MgO_{(s)} + 2HCl_{(aq)} \rightarrow MgCl_{2(aq)} + H_2O_{(l)}$
• Sulphur dioxide ($SO_2$): This is an acidic oxide. It dissolves in water to form sulfurous acid ($H_2SO_3$) and reacts with bases.
  Reaction with water: $SO_2 + H_2O \rightleftharpoons H_2SO_3$

Identifying the Amphoteric Oxide

From the analysis, only Zinc oxide ($ZnO$) shows amphoteric properties, reacting with both acids and bases.